Java example source code file (psScavenge.cpp)
The psScavenge.cpp Java example source code
/*
* Copyright (c) 2002, 2013, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*
*/
#include "precompiled.hpp"
#include "classfile/symbolTable.hpp"
#include "code/codeCache.hpp"
#include "gc_implementation/parallelScavenge/cardTableExtension.hpp"
#include "gc_implementation/parallelScavenge/gcTaskManager.hpp"
#include "gc_implementation/parallelScavenge/parallelScavengeHeap.hpp"
#include "gc_implementation/parallelScavenge/psAdaptiveSizePolicy.hpp"
#include "gc_implementation/parallelScavenge/psMarkSweep.hpp"
#include "gc_implementation/parallelScavenge/psParallelCompact.hpp"
#include "gc_implementation/parallelScavenge/psScavenge.inline.hpp"
#include "gc_implementation/parallelScavenge/psTasks.hpp"
#include "gc_implementation/shared/gcHeapSummary.hpp"
#include "gc_implementation/shared/gcTimer.hpp"
#include "gc_implementation/shared/gcTrace.hpp"
#include "gc_implementation/shared/gcTraceTime.hpp"
#include "gc_implementation/shared/isGCActiveMark.hpp"
#include "gc_implementation/shared/spaceDecorator.hpp"
#include "gc_interface/gcCause.hpp"
#include "memory/collectorPolicy.hpp"
#include "memory/gcLocker.inline.hpp"
#include "memory/referencePolicy.hpp"
#include "memory/referenceProcessor.hpp"
#include "memory/resourceArea.hpp"
#include "oops/oop.inline.hpp"
#include "oops/oop.psgc.inline.hpp"
#include "runtime/biasedLocking.hpp"
#include "runtime/fprofiler.hpp"
#include "runtime/handles.inline.hpp"
#include "runtime/threadCritical.hpp"
#include "runtime/vmThread.hpp"
#include "runtime/vm_operations.hpp"
#include "services/memoryService.hpp"
#include "utilities/stack.inline.hpp"
HeapWord* PSScavenge::_to_space_top_before_gc = NULL;
int PSScavenge::_consecutive_skipped_scavenges = 0;
ReferenceProcessor* PSScavenge::_ref_processor = NULL;
CardTableExtension* PSScavenge::_card_table = NULL;
bool PSScavenge::_survivor_overflow = false;
uint PSScavenge::_tenuring_threshold = 0;
HeapWord* PSScavenge::_young_generation_boundary = NULL;
uintptr_t PSScavenge::_young_generation_boundary_compressed = 0;
elapsedTimer PSScavenge::_accumulated_time;
STWGCTimer PSScavenge::_gc_timer;
ParallelScavengeTracer PSScavenge::_gc_tracer;
Stack<markOop, mtGC> PSScavenge::_preserved_mark_stack;
Stack<oop, mtGC> PSScavenge::_preserved_oop_stack;
CollectorCounters* PSScavenge::_counters = NULL;
// Define before use
class PSIsAliveClosure: public BoolObjectClosure {
public:
bool do_object_b(oop p) {
return (!PSScavenge::is_obj_in_young(p)) || p->is_forwarded();
}
};
PSIsAliveClosure PSScavenge::_is_alive_closure;
class PSKeepAliveClosure: public OopClosure {
protected:
MutableSpace* _to_space;
PSPromotionManager* _promotion_manager;
public:
PSKeepAliveClosure(PSPromotionManager* pm) : _promotion_manager(pm) {
ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
_to_space = heap->young_gen()->to_space();
assert(_promotion_manager != NULL, "Sanity");
}
template <class T> void do_oop_work(T* p) {
assert (!oopDesc::is_null(*p), "expected non-null ref");
assert ((oopDesc::load_decode_heap_oop_not_null(p))->is_oop(),
"expected an oop while scanning weak refs");
// Weak refs may be visited more than once.
if (PSScavenge::should_scavenge(p, _to_space)) {
PSScavenge::copy_and_push_safe_barrier<T, /*promote_immediately=*/false>(_promotion_manager, p);
}
}
virtual void do_oop(oop* p) { PSKeepAliveClosure::do_oop_work(p); }
virtual void do_oop(narrowOop* p) { PSKeepAliveClosure::do_oop_work(p); }
};
class PSEvacuateFollowersClosure: public VoidClosure {
private:
PSPromotionManager* _promotion_manager;
public:
PSEvacuateFollowersClosure(PSPromotionManager* pm) : _promotion_manager(pm) {}
virtual void do_void() {
assert(_promotion_manager != NULL, "Sanity");
_promotion_manager->drain_stacks(true);
guarantee(_promotion_manager->stacks_empty(),
"stacks should be empty at this point");
}
};
class PSPromotionFailedClosure : public ObjectClosure {
virtual void do_object(oop obj) {
if (obj->is_forwarded()) {
obj->init_mark();
}
}
};
class PSRefProcTaskProxy: public GCTask {
typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
ProcessTask & _rp_task;
uint _work_id;
public:
PSRefProcTaskProxy(ProcessTask & rp_task, uint work_id)
: _rp_task(rp_task),
_work_id(work_id)
{ }
private:
virtual char* name() { return (char *)"Process referents by policy in parallel"; }
virtual void do_it(GCTaskManager* manager, uint which);
};
void PSRefProcTaskProxy::do_it(GCTaskManager* manager, uint which)
{
PSPromotionManager* promotion_manager =
PSPromotionManager::gc_thread_promotion_manager(which);
assert(promotion_manager != NULL, "sanity check");
PSKeepAliveClosure keep_alive(promotion_manager);
PSEvacuateFollowersClosure evac_followers(promotion_manager);
PSIsAliveClosure is_alive;
_rp_task.work(_work_id, is_alive, keep_alive, evac_followers);
}
class PSRefEnqueueTaskProxy: public GCTask {
typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
EnqueueTask& _enq_task;
uint _work_id;
public:
PSRefEnqueueTaskProxy(EnqueueTask& enq_task, uint work_id)
: _enq_task(enq_task),
_work_id(work_id)
{ }
virtual char* name() { return (char *)"Enqueue reference objects in parallel"; }
virtual void do_it(GCTaskManager* manager, uint which)
{
_enq_task.work(_work_id);
}
};
class PSRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
virtual void execute(ProcessTask& task);
virtual void execute(EnqueueTask& task);
};
void PSRefProcTaskExecutor::execute(ProcessTask& task)
{
GCTaskQueue* q = GCTaskQueue::create();
GCTaskManager* manager = ParallelScavengeHeap::gc_task_manager();
for(uint i=0; i < manager->active_workers(); i++) {
q->enqueue(new PSRefProcTaskProxy(task, i));
}
ParallelTaskTerminator terminator(manager->active_workers(),
(TaskQueueSetSuper*) PSPromotionManager::stack_array_depth());
if (task.marks_oops_alive() && manager->active_workers() > 1) {
for (uint j = 0; j < manager->active_workers(); j++) {
q->enqueue(new StealTask(&terminator));
}
}
manager->execute_and_wait(q);
}
void PSRefProcTaskExecutor::execute(EnqueueTask& task)
{
GCTaskQueue* q = GCTaskQueue::create();
GCTaskManager* manager = ParallelScavengeHeap::gc_task_manager();
for(uint i=0; i < manager->active_workers(); i++) {
q->enqueue(new PSRefEnqueueTaskProxy(task, i));
}
manager->execute_and_wait(q);
}
// This method contains all heap specific policy for invoking scavenge.
// PSScavenge::invoke_no_policy() will do nothing but attempt to
// scavenge. It will not clean up after failed promotions, bail out if
// we've exceeded policy time limits, or any other special behavior.
// All such policy should be placed here.
//
// Note that this method should only be called from the vm_thread while
// at a safepoint!
bool PSScavenge::invoke() {
assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread");
assert(!Universe::heap()->is_gc_active(), "not reentrant");
ParallelScavengeHeap* const heap = (ParallelScavengeHeap*)Universe::heap();
assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
PSAdaptiveSizePolicy* policy = heap->size_policy();
IsGCActiveMark mark;
const bool scavenge_done = PSScavenge::invoke_no_policy();
const bool need_full_gc = !scavenge_done ||
policy->should_full_GC(heap->old_gen()->free_in_bytes());
bool full_gc_done = false;
if (UsePerfData) {
PSGCAdaptivePolicyCounters* const counters = heap->gc_policy_counters();
const int ffs_val = need_full_gc ? full_follows_scavenge : not_skipped;
counters->update_full_follows_scavenge(ffs_val);
}
if (need_full_gc) {
GCCauseSetter gccs(heap, GCCause::_adaptive_size_policy);
CollectorPolicy* cp = heap->collector_policy();
const bool clear_all_softrefs = cp->should_clear_all_soft_refs();
if (UseParallelOldGC) {
full_gc_done = PSParallelCompact::invoke_no_policy(clear_all_softrefs);
} else {
full_gc_done = PSMarkSweep::invoke_no_policy(clear_all_softrefs);
}
}
return full_gc_done;
}
// This method contains no policy. You should probably
// be calling invoke() instead.
bool PSScavenge::invoke_no_policy() {
assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread");
assert(_preserved_mark_stack.is_empty(), "should be empty");
assert(_preserved_oop_stack.is_empty(), "should be empty");
_gc_timer.register_gc_start();
TimeStamp scavenge_entry;
TimeStamp scavenge_midpoint;
TimeStamp scavenge_exit;
scavenge_entry.update();
if (GC_locker::check_active_before_gc()) {
return false;
}
ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
GCCause::Cause gc_cause = heap->gc_cause();
assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
// Check for potential problems.
if (!should_attempt_scavenge()) {
return false;
}
_gc_tracer.report_gc_start(heap->gc_cause(), _gc_timer.gc_start());
bool promotion_failure_occurred = false;
PSYoungGen* young_gen = heap->young_gen();
PSOldGen* old_gen = heap->old_gen();
PSAdaptiveSizePolicy* size_policy = heap->size_policy();
heap->increment_total_collections();
AdaptiveSizePolicyOutput(size_policy, heap->total_collections());
if ((gc_cause != GCCause::_java_lang_system_gc) ||
UseAdaptiveSizePolicyWithSystemGC) {
// Gather the feedback data for eden occupancy.
young_gen->eden_space()->accumulate_statistics();
}
if (ZapUnusedHeapArea) {
// Save information needed to minimize mangling
heap->record_gen_tops_before_GC();
}
heap->print_heap_before_gc();
heap->trace_heap_before_gc(&_gc_tracer);
assert(!NeverTenure || _tenuring_threshold == markOopDesc::max_age + 1, "Sanity");
assert(!AlwaysTenure || _tenuring_threshold == 0, "Sanity");
size_t prev_used = heap->used();
// Fill in TLABs
heap->accumulate_statistics_all_tlabs();
heap->ensure_parsability(true); // retire TLABs
if (VerifyBeforeGC && heap->total_collections() >= VerifyGCStartAt) {
HandleMark hm; // Discard invalid handles created during verification
Universe::verify(" VerifyBeforeGC:");
}
{
ResourceMark rm;
HandleMark hm;
gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps);
TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
GCTraceTime t1(GCCauseString("GC", gc_cause), PrintGC, !PrintGCDetails, NULL);
TraceCollectorStats tcs(counters());
TraceMemoryManagerStats tms(false /* not full GC */,gc_cause);
if (TraceGen0Time) accumulated_time()->start();
// Let the size policy know we're starting
size_policy->minor_collection_begin();
// Verify the object start arrays.
if (VerifyObjectStartArray &&
VerifyBeforeGC) {
old_gen->verify_object_start_array();
}
// Verify no unmarked old->young roots
if (VerifyRememberedSets) {
CardTableExtension::verify_all_young_refs_imprecise();
}
if (!ScavengeWithObjectsInToSpace) {
assert(young_gen->to_space()->is_empty(),
"Attempt to scavenge with live objects in to_space");
young_gen->to_space()->clear(SpaceDecorator::Mangle);
} else if (ZapUnusedHeapArea) {
young_gen->to_space()->mangle_unused_area();
}
save_to_space_top_before_gc();
COMPILER2_PRESENT(DerivedPointerTable::clear());
reference_processor()->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/);
reference_processor()->setup_policy(false);
// We track how much was promoted to the next generation for
// the AdaptiveSizePolicy.
size_t old_gen_used_before = old_gen->used_in_bytes();
// For PrintGCDetails
size_t young_gen_used_before = young_gen->used_in_bytes();
// Reset our survivor overflow.
set_survivor_overflow(false);
// We need to save the old top values before
// creating the promotion_manager. We pass the top
// values to the card_table, to prevent it from
// straying into the promotion labs.
HeapWord* old_top = old_gen->object_space()->top();
// Release all previously held resources
gc_task_manager()->release_all_resources();
// Set the number of GC threads to be used in this collection
gc_task_manager()->set_active_gang();
gc_task_manager()->task_idle_workers();
// Get the active number of workers here and use that value
// throughout the methods.
uint active_workers = gc_task_manager()->active_workers();
heap->set_par_threads(active_workers);
PSPromotionManager::pre_scavenge();
// We'll use the promotion manager again later.
PSPromotionManager* promotion_manager = PSPromotionManager::vm_thread_promotion_manager();
{
GCTraceTime tm("Scavenge", false, false, &_gc_timer);
ParallelScavengeHeap::ParStrongRootsScope psrs;
GCTaskQueue* q = GCTaskQueue::create();
if (!old_gen->object_space()->is_empty()) {
// There are only old-to-young pointers if there are objects
// in the old gen.
uint stripe_total = active_workers;
for(uint i=0; i < stripe_total; i++) {
q->enqueue(new OldToYoungRootsTask(old_gen, old_top, i, stripe_total));
}
}
q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::universe));
q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::jni_handles));
// We scan the thread roots in parallel
Threads::create_thread_roots_tasks(q);
q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::object_synchronizer));
q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::flat_profiler));
q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::management));
q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::system_dictionary));
q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::class_loader_data));
q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::jvmti));
q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::code_cache));
ParallelTaskTerminator terminator(
active_workers,
(TaskQueueSetSuper*) promotion_manager->stack_array_depth());
if (active_workers > 1) {
for (uint j = 0; j < active_workers; j++) {
q->enqueue(new StealTask(&terminator));
}
}
gc_task_manager()->execute_and_wait(q);
}
scavenge_midpoint.update();
// Process reference objects discovered during scavenge
{
GCTraceTime tm("References", false, false, &_gc_timer);
reference_processor()->setup_policy(false); // not always_clear
reference_processor()->set_active_mt_degree(active_workers);
PSKeepAliveClosure keep_alive(promotion_manager);
PSEvacuateFollowersClosure evac_followers(promotion_manager);
ReferenceProcessorStats stats;
if (reference_processor()->processing_is_mt()) {
PSRefProcTaskExecutor task_executor;
stats = reference_processor()->process_discovered_references(
&_is_alive_closure, &keep_alive, &evac_followers, &task_executor,
&_gc_timer);
} else {
stats = reference_processor()->process_discovered_references(
&_is_alive_closure, &keep_alive, &evac_followers, NULL, &_gc_timer);
}
_gc_tracer.report_gc_reference_stats(stats);
// Enqueue reference objects discovered during scavenge.
if (reference_processor()->processing_is_mt()) {
PSRefProcTaskExecutor task_executor;
reference_processor()->enqueue_discovered_references(&task_executor);
} else {
reference_processor()->enqueue_discovered_references(NULL);
}
}
GCTraceTime tm("StringTable", false, false, &_gc_timer);
// Unlink any dead interned Strings and process the remaining live ones.
PSScavengeRootsClosure root_closure(promotion_manager);
StringTable::unlink_or_oops_do(&_is_alive_closure, &root_closure);
// Finally, flush the promotion_manager's labs, and deallocate its stacks.
promotion_failure_occurred = PSPromotionManager::post_scavenge(_gc_tracer);
if (promotion_failure_occurred) {
clean_up_failed_promotion();
if (PrintGC) {
gclog_or_tty->print("--");
}
}
// Let the size policy know we're done. Note that we count promotion
// failure cleanup time as part of the collection (otherwise, we're
// implicitly saying it's mutator time).
size_policy->minor_collection_end(gc_cause);
if (!promotion_failure_occurred) {
// Swap the survivor spaces.
young_gen->eden_space()->clear(SpaceDecorator::Mangle);
young_gen->from_space()->clear(SpaceDecorator::Mangle);
young_gen->swap_spaces();
size_t survived = young_gen->from_space()->used_in_bytes();
size_t promoted = old_gen->used_in_bytes() - old_gen_used_before;
size_policy->update_averages(_survivor_overflow, survived, promoted);
// A successful scavenge should restart the GC time limit count which is
// for full GC's.
size_policy->reset_gc_overhead_limit_count();
if (UseAdaptiveSizePolicy) {
// Calculate the new survivor size and tenuring threshold
if (PrintAdaptiveSizePolicy) {
gclog_or_tty->print("AdaptiveSizeStart: ");
gclog_or_tty->stamp();
gclog_or_tty->print_cr(" collection: %d ",
heap->total_collections());
if (Verbose) {
gclog_or_tty->print("old_gen_capacity: %d young_gen_capacity: %d",
old_gen->capacity_in_bytes(), young_gen->capacity_in_bytes());
}
}
if (UsePerfData) {
PSGCAdaptivePolicyCounters* counters = heap->gc_policy_counters();
counters->update_old_eden_size(
size_policy->calculated_eden_size_in_bytes());
counters->update_old_promo_size(
size_policy->calculated_promo_size_in_bytes());
counters->update_old_capacity(old_gen->capacity_in_bytes());
counters->update_young_capacity(young_gen->capacity_in_bytes());
counters->update_survived(survived);
counters->update_promoted(promoted);
counters->update_survivor_overflowed(_survivor_overflow);
}
size_t survivor_limit =
size_policy->max_survivor_size(young_gen->max_size());
_tenuring_threshold =
size_policy->compute_survivor_space_size_and_threshold(
_survivor_overflow,
_tenuring_threshold,
survivor_limit);
if (PrintTenuringDistribution) {
gclog_or_tty->cr();
gclog_or_tty->print_cr("Desired survivor size " SIZE_FORMAT " bytes, new threshold %u (max %u)",
size_policy->calculated_survivor_size_in_bytes(),
_tenuring_threshold, MaxTenuringThreshold);
}
if (UsePerfData) {
PSGCAdaptivePolicyCounters* counters = heap->gc_policy_counters();
counters->update_tenuring_threshold(_tenuring_threshold);
counters->update_survivor_size_counters();
}
// Do call at minor collections?
// Don't check if the size_policy is ready at this
// level. Let the size_policy check that internally.
if (UseAdaptiveSizePolicy &&
UseAdaptiveGenerationSizePolicyAtMinorCollection &&
((gc_cause != GCCause::_java_lang_system_gc) ||
UseAdaptiveSizePolicyWithSystemGC)) {
// Calculate optimial free space amounts
assert(young_gen->max_size() >
young_gen->from_space()->capacity_in_bytes() +
young_gen->to_space()->capacity_in_bytes(),
"Sizes of space in young gen are out-of-bounds");
size_t young_live = young_gen->used_in_bytes();
size_t eden_live = young_gen->eden_space()->used_in_bytes();
size_t cur_eden = young_gen->eden_space()->capacity_in_bytes();
size_t max_old_gen_size = old_gen->max_gen_size();
size_t max_eden_size = young_gen->max_size() -
young_gen->from_space()->capacity_in_bytes() -
young_gen->to_space()->capacity_in_bytes();
// Used for diagnostics
size_policy->clear_generation_free_space_flags();
size_policy->compute_eden_space_size(young_live,
eden_live,
cur_eden,
max_eden_size,
false /* not full gc*/);
size_policy->check_gc_overhead_limit(young_live,
eden_live,
max_old_gen_size,
max_eden_size,
false /* not full gc*/,
gc_cause,
heap->collector_policy());
size_policy->decay_supplemental_growth(false /* not full gc*/);
}
// Resize the young generation at every collection
// even if new sizes have not been calculated. This is
// to allow resizes that may have been inhibited by the
// relative location of the "to" and "from" spaces.
// Resizing the old gen at minor collects can cause increases
// that don't feed back to the generation sizing policy until
// a major collection. Don't resize the old gen here.
heap->resize_young_gen(size_policy->calculated_eden_size_in_bytes(),
size_policy->calculated_survivor_size_in_bytes());
if (PrintAdaptiveSizePolicy) {
gclog_or_tty->print_cr("AdaptiveSizeStop: collection: %d ",
heap->total_collections());
}
}
// Update the structure of the eden. With NUMA-eden CPU hotplugging or offlining can
// cause the change of the heap layout. Make sure eden is reshaped if that's the case.
// Also update() will case adaptive NUMA chunk resizing.
assert(young_gen->eden_space()->is_empty(), "eden space should be empty now");
young_gen->eden_space()->update();
heap->gc_policy_counters()->update_counters();
heap->resize_all_tlabs();
assert(young_gen->to_space()->is_empty(), "to space should be empty now");
}
COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
NOT_PRODUCT(reference_processor()->verify_no_references_recorded());
{
GCTraceTime tm("Prune Scavenge Root Methods", false, false, &_gc_timer);
CodeCache::prune_scavenge_root_nmethods();
}
// Re-verify object start arrays
if (VerifyObjectStartArray &&
VerifyAfterGC) {
old_gen->verify_object_start_array();
}
// Verify all old -> young cards are now precise
if (VerifyRememberedSets) {
// Precise verification will give false positives. Until this is fixed,
// use imprecise verification.
// CardTableExtension::verify_all_young_refs_precise();
CardTableExtension::verify_all_young_refs_imprecise();
}
if (TraceGen0Time) accumulated_time()->stop();
if (PrintGC) {
if (PrintGCDetails) {
// Don't print a GC timestamp here. This is after the GC so
// would be confusing.
young_gen->print_used_change(young_gen_used_before);
}
heap->print_heap_change(prev_used);
}
// Track memory usage and detect low memory
MemoryService::track_memory_usage();
heap->update_counters();
gc_task_manager()->release_idle_workers();
}
if (VerifyAfterGC && heap->total_collections() >= VerifyGCStartAt) {
HandleMark hm; // Discard invalid handles created during verification
Universe::verify(" VerifyAfterGC:");
}
heap->print_heap_after_gc();
heap->trace_heap_after_gc(&_gc_tracer);
_gc_tracer.report_tenuring_threshold(tenuring_threshold());
if (ZapUnusedHeapArea) {
young_gen->eden_space()->check_mangled_unused_area_complete();
young_gen->from_space()->check_mangled_unused_area_complete();
young_gen->to_space()->check_mangled_unused_area_complete();
}
scavenge_exit.update();
if (PrintGCTaskTimeStamps) {
tty->print_cr("VM-Thread " INT64_FORMAT " " INT64_FORMAT " " INT64_FORMAT,
scavenge_entry.ticks(), scavenge_midpoint.ticks(),
scavenge_exit.ticks());
gc_task_manager()->print_task_time_stamps();
}
#ifdef TRACESPINNING
ParallelTaskTerminator::print_termination_counts();
#endif
_gc_timer.register_gc_end();
_gc_tracer.report_gc_end(_gc_timer.gc_end(), _gc_timer.time_partitions());
return !promotion_failure_occurred;
}
// This method iterates over all objects in the young generation,
// unforwarding markOops. It then restores any preserved mark oops,
// and clears the _preserved_mark_stack.
void PSScavenge::clean_up_failed_promotion() {
ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
PSYoungGen* young_gen = heap->young_gen();
{
ResourceMark rm;
// Unforward all pointers in the young gen.
PSPromotionFailedClosure unforward_closure;
young_gen->object_iterate(&unforward_closure);
if (PrintGC && Verbose) {
gclog_or_tty->print_cr("Restoring %d marks", _preserved_oop_stack.size());
}
// Restore any saved marks.
while (!_preserved_oop_stack.is_empty()) {
oop obj = _preserved_oop_stack.pop();
markOop mark = _preserved_mark_stack.pop();
obj->set_mark(mark);
}
// Clear the preserved mark and oop stack caches.
_preserved_mark_stack.clear(true);
_preserved_oop_stack.clear(true);
}
// Reset the PromotionFailureALot counters.
NOT_PRODUCT(Universe::heap()->reset_promotion_should_fail();)
}
// This method is called whenever an attempt to promote an object
// fails. Some markOops will need preservation, some will not. Note
// that the entire eden is traversed after a failed promotion, with
// all forwarded headers replaced by the default markOop. This means
// it is not necessary to preserve most markOops.
void PSScavenge::oop_promotion_failed(oop obj, markOop obj_mark) {
if (obj_mark->must_be_preserved_for_promotion_failure(obj)) {
// Should use per-worker private stacks here rather than
// locking a common pair of stacks.
ThreadCritical tc;
_preserved_oop_stack.push(obj);
_preserved_mark_stack.push(obj_mark);
}
}
bool PSScavenge::should_attempt_scavenge() {
ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
PSGCAdaptivePolicyCounters* counters = heap->gc_policy_counters();
if (UsePerfData) {
counters->update_scavenge_skipped(not_skipped);
}
PSYoungGen* young_gen = heap->young_gen();
PSOldGen* old_gen = heap->old_gen();
if (!ScavengeWithObjectsInToSpace) {
// Do not attempt to promote unless to_space is empty
if (!young_gen->to_space()->is_empty()) {
_consecutive_skipped_scavenges++;
if (UsePerfData) {
counters->update_scavenge_skipped(to_space_not_empty);
}
return false;
}
}
// Test to see if the scavenge will likely fail.
PSAdaptiveSizePolicy* policy = heap->size_policy();
// A similar test is done in the policy's should_full_GC(). If this is
// changed, decide if that test should also be changed.
size_t avg_promoted = (size_t) policy->padded_average_promoted_in_bytes();
size_t promotion_estimate = MIN2(avg_promoted, young_gen->used_in_bytes());
bool result = promotion_estimate < old_gen->free_in_bytes();
if (PrintGCDetails && Verbose) {
gclog_or_tty->print(result ? " do scavenge: " : " skip scavenge: ");
gclog_or_tty->print_cr(" average_promoted " SIZE_FORMAT
" padded_average_promoted " SIZE_FORMAT
" free in old gen " SIZE_FORMAT,
(size_t) policy->average_promoted_in_bytes(),
(size_t) policy->padded_average_promoted_in_bytes(),
old_gen->free_in_bytes());
if (young_gen->used_in_bytes() <
(size_t) policy->padded_average_promoted_in_bytes()) {
gclog_or_tty->print_cr(" padded_promoted_average is greater"
" than maximum promotion = " SIZE_FORMAT, young_gen->used_in_bytes());
}
}
if (result) {
_consecutive_skipped_scavenges = 0;
} else {
_consecutive_skipped_scavenges++;
if (UsePerfData) {
counters->update_scavenge_skipped(promoted_too_large);
}
}
return result;
}
// Used to add tasks
GCTaskManager* const PSScavenge::gc_task_manager() {
assert(ParallelScavengeHeap::gc_task_manager() != NULL,
"shouldn't return NULL");
return ParallelScavengeHeap::gc_task_manager();
}
void PSScavenge::initialize() {
// Arguments must have been parsed
if (AlwaysTenure) {
_tenuring_threshold = 0;
} else if (NeverTenure) {
_tenuring_threshold = markOopDesc::max_age + 1;
} else {
// We want to smooth out our startup times for the AdaptiveSizePolicy
_tenuring_threshold = (UseAdaptiveSizePolicy) ? InitialTenuringThreshold :
MaxTenuringThreshold;
}
ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
PSYoungGen* young_gen = heap->young_gen();
PSOldGen* old_gen = heap->old_gen();
// Set boundary between young_gen and old_gen
assert(old_gen->reserved().end() <= young_gen->eden_space()->bottom(),
"old above young");
set_young_generation_boundary(young_gen->eden_space()->bottom());
// Initialize ref handling object for scavenging.
MemRegion mr = young_gen->reserved();
_ref_processor =
new ReferenceProcessor(mr, // span
ParallelRefProcEnabled && (ParallelGCThreads > 1), // mt processing
(int) ParallelGCThreads, // mt processing degree
true, // mt discovery
(int) ParallelGCThreads, // mt discovery degree
true, // atomic_discovery
NULL, // header provides liveness info
false); // next field updates do not need write barrier
// Cache the cardtable
BarrierSet* bs = Universe::heap()->barrier_set();
assert(bs->kind() == BarrierSet::CardTableModRef, "Wrong barrier set kind");
_card_table = (CardTableExtension*)bs;
_counters = new CollectorCounters("PSScavenge", 0);
}
Other Java examples (source code examples)Here is a short list of links related to this Java psScavenge.cpp source code file: |
The search page
Other Java source code examples at this package level
Click here to learn more about this project
